74 vette headlights

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Jul 23, 2008 | 07:14 PM

silverado08

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74 vette headlights

i have a 74 vette and the head lights dont come up when you turn on the headlight switch . i know they are vac operated and i have vac at the hose coming out of the firewall . does vac open or shut them? does any body have a diagram of the system. i am familier with the mechanical, front and rear suspension and engines on vettes having worked at a chevy dealer for 37 years and recently retired. never got into the headlight system that i can remember. thanx

Jul 23, 2008 | 07:32 PM

Lights

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From: Burgaw North Carolina

It is my understanding that the vac opens them. Most likely the ruber sill in the actuator has gone bad and not pulling the vacuum. The sill is in the can on each light and therefore needs to be airtight in order for the vacuum in the can to be created. There is a rod that runs out the front of the can connecting to the headlight assembly. The rod goes through the sill I'm speaking of.

Jul 24, 2008 | 12:53 PM

C3 4ME

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From: Glen Allen, VA

Actually vacumn is what keeps them closed, that much I know for sure. I'm not exactly sure of what makes what work but I do know if you see the boot on the rod coming out of the front of the actuators is torn, chances are the seal inside is also no good. In this case I'd remove hte actuators and put a seal kit in them, they aren't expensive, something like $25 a kit. That's what I did for mine when they wouldnt' come up and it fixed them. On mine if you raised them by hand, they would stay up if you had the vavle under the steering column pulled down. As soon as you pushed the valve back in they would go down on their own.

Jul 25, 2008 | 01:04 AM

hwcoop

Melting Slicks

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From: Airdrie Alberta

here is one site with vacume troubleshooting..there are a number out there
http://vetteworks.tripod.com./techdocuments/Vaccum.html

I found on mine after replacing my actuator seals that they would still not come up when pulling the light switch. After taking the light switch apart and cleaning/resealing the rubber gasket they worked great.
I was lucky at the time my windshield was out so I could pull the dash pad off and the switch was right there

Jul 25, 2008 | 05:12 PM

Peterbuilt

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From: mount holly NC

2025 c3 ('74-'82) of the Year Finalist - Unmodified

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That tripod diagram is wrong, the hose from the manifold has to connect to the headlight port closest to the driver, and the hose from the headlight switch port closest to the firewall has to go to the bottom port on the pull down switch, PG

Jul 25, 2008 | 05:17 PM

Peterbuilt

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From: mount holly NC

2025 c3 ('74-'82) of the Year Finalist - Unmodified

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The corrected diagram for 73-79 is at http://s243.photobucket.com/albums/ff91/petes74ttop/

Jul 25, 2008 | 07:58 PM

Paul L

Team Owner

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From: Ontario

You may wish to post this in Corvette FAQs. And BarryK's site.

http://lbfun.com/Corvette/Tech/vettetech.html

Last edited by Paul L; Jul 25, 2008 at 08:01 PM.

Jul 26, 2008 | 12:25 AM

Peterbuilt

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From: mount holly NC

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Hi Paul67, thanks for the heads up, Barry & Linda's site has it correct on the "Corrected Link" if you want to post it FAQ's feel free to do so. I've learned a lot from this forum and for once I can contribute to it. PG.